Passive devices for 3D non-volatile memory

ABSTRACT

Passive devices such as resistors and capacitors are provided for a 3D non-volatile memory device. In a peripheral area of a substrate, a passive device includes alternating layers of a dielectric such as oxide and a conductive material such as heavily doped polysilicon or metal silicide in a stack. The substrate includes one or more lower metal layers connected to circuitry. One or more upper metal layers are provided above the stack. Contact structures extend from the layers of conductive material to portions of the one or more upper metal layers so that the layers of conductive material are connected to one another in parallel, for a capacitor, or serially, for a resistor, by the contact structures and the at least one upper metal layer. Additional contact structures can connect the circuitry to the one or more upper metal layers.

BACKGROUND

The present technology relates to non-volatile memory.

Recently, ultra high density storage devices have been proposed using a3D stacked memory structure sometimes referred to as a bit cost scalable(BiCS) architecture. For example, a 3D NAND stackable memory device canbe formed from an array of alternating conductive and dielectric layers.A memory hole is drilled in the layers to define many memory layerssimultaneously. A NAND string is then formed by filling the memory holewith appropriate materials. A straight NAND string extends in one memoryhole, while a pipe- or U-shaped NAND string (P-BiCS) includes a pair ofvertical columns of memory cells which extend in two memory holes andwhich are joined by a bottom back gate. Control gates of the memorycells are provided by the conductive layers.

However, there is a continuing need to reduce the size of such memorydevices.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like-numbered elements correspond to one another.

FIG. 1A is a perspective view of a 3D stacked non-volatile memory device100 in which a plane of memory cells is arranged in separate subarrays.

FIG. 1B is a perspective view of a 3D stacked non-volatile memory device150 in which a plane of memory cells is arranged in contiguoussubarrays.

FIG. 2A depicts a top view of the 3D stacked non-volatile memory device100 of FIG. 1A.

FIG. 2B depicts a top view of the 3D stacked non-volatile memory device150 of FIG. 1B.

FIG. 3 depicts a top view of one embodiment of the plane 170 of the 3Dstacked non-volatile memory device 150 of FIG. 1B, showing at least oneinterconnect area having two interconnects and at least one cell areahaving four subarray regions.

FIG. 4 depicts a top view of a plane 470 of the 3D stacked non-volatilememory device 150 of FIG. 1B, showing at least one interconnect areahaving eight interconnects and at least one cell area having foursubarray regions.

FIG. 5 depicts a top view of one embodiment of a plane 570 of the 3Dstacked non-volatile memory device 150 of FIG. 1B, showing at least oneinterconnect area having two interconnects.

FIG. 6 depicts a method for fabricating a 3D stacked non-volatile memorydevice according to the structures of FIGS. 8-14B, where a wet etch isperformed via slits.

FIG. 7 depicts a method for fabricating a 3D stacked non-volatile memorydevice, corresponding to the structures of FIGS. 15-21A, where a wetetch is performed via memory holes.

FIG. 8 depicts a layered semiconductor material 800 which is consistentwith a cross-sectional view of the region 530 of the 3D stackednon-volatile memory device of FIG. 5 along the line 550, showing slitsand memory holes in the cell areas CA3 and CA4, and slits in theinterconnect area IA1.

FIG. 9 depicts a layered semiconductor material 900 which is obtainedfrom the layered semiconductor material 800 after performing a wet etchvia the slits in the cell areas CA3 and CA4.

FIG. 10 depicts a layered semiconductor material 1000 which is obtainedfrom the layered semiconductor material 900 after filling in voids withinsulation via the slits in the cell areas CA3 and CA4.

FIG. 11 depicts a layered semiconductor material 1100 which is obtainedfrom the layered semiconductor material 1000 after cleaning out theslits in the cell areas CA3 and CA4 and in the interconnect area IA1.

FIG. 12 depicts a layered semiconductor material 1200 which is obtainedfrom the layered semiconductor material 1100 after performingsilicidation via the slits in the cell areas CA3 and CA4, and in theinterconnect area IA1.

FIG. 13 depicts a layered semiconductor material 1300 which is obtainedfrom the layered semiconductor material 1200 after cleaning out thememory holes in the cell areas CA3 and CA4.

FIG. 14A depicts a layered semiconductor material 1400 which is obtainedfrom the layered semiconductor material 1350 after filling in the memoryholes.

FIG. 14B depicts a cross-sectional view of the memory hole H1 of FIG.14A.

FIG. 15 depicts a top view of another embodiment of a plane 1569 of the3D stacked non-volatile memory device 150 of FIG. 1B, showing at leastone interconnect area having six interconnects and at least one cellarea.

FIG. 16 depicts a layered semiconductor material 1600 which isconsistent with a cross-sectional view of the plane 1569 of FIG. 15along the line 1550, showing slits and memory holes in the cell areasCA5 and CA6, and slits in the interconnect area IA3.

FIG. 17 depicts a layered semiconductor material 1700 which is obtainedfrom the layered semiconductor material 1600 after performing a wet etchvia the memory holes in the cell areas CA5 and CA6.

FIG. 18 depicts a layered semiconductor material 1800 which is obtainedfrom the layered semiconductor material 1700 after filling in memoryholes and recesses between heavily doped poly layers via the memoryholes in the cell areas CA5 and CA6.

FIG. 19 depicts a layered semiconductor material 1900 which is obtainedfrom the layered semiconductor material 1800 after cleaning out theslits in the cell areas CA5 and CA6 and the in the interconnect areaIA3.

FIG. 20A depicts a layered semiconductor material 2000 which is obtainedfrom the layered semiconductor material 1900 after performingsilicidation via the slits in the cell areas CA5 and CA6 and in theinterconnect area IA3.

FIG. 20B depicts a layered semiconductor material 2080 which is obtainedfrom the layered semiconductor material 2000 after depositing insulationin the slits in the interconnect area IA3.

FIG. 21A depicts details of region 2100 in FIG. 20B.

FIG. 22A depicts a cross-sectional view along line 580 of FIG. 5 of theplane 570, showing terraced portions 2250 and 2252 of the cell area CA3.

FIG. 22B depicts contact structures of the terraced portion 2252 of thecell area CA3 of FIG. 22A.

FIG. 22C depicts an example alternative terraced portion of a cell areawith contact structures.

FIG. 23A depicts a cross-sectional view along line 590 of FIG. 5 of theplane 570, showing terraced portions 2350 and 2352 of the interconnectarea IA1.

FIG. 23B depicts contact structures of the terraced portion 2352 of thecell area CA3 of FIG. 23A.

FIG. 23C depicts a cross-sectional view along line 440 of a portion ofthe plane 470 of FIG. 4.

FIG. 24 depicts an end view of the plane 570 of FIG. 5, showing contactstructures.

FIG. 25 depicts a top view of a peripheral region of a substrate whichincludes stacked interconnects 2500.

FIG. 26A depicts a top view of another embodiment of the plane 570 ofFIG. 5 as plane 2600.

FIG. 26B depicts a cross-sectional view along line 2690 of FIG. 26A,showing heavily doped polysilicon layers connected in parallel.

FIG. 27A depicts a capacitor in a 2D memory device.

FIG. 27B depicts a capacitor in a 3D memory device.

FIG. 28A depicts a top view of one embodiment of a passive device as acapacitor in the peripheral region 182 of the 3D stacked non-volatilememory device 150 of FIG. 1B.

FIG. 28B depicts a top view of another embodiment of a passive device asa resistor in the peripheral region 182 of the 3D stacked non-volatilememory device 150 of FIG. 1B.

FIG. 28C depicts a top view of another embodiment of a passive device asmultiple capacitors in the peripheral region 182 of the 3D stackednon-volatile memory device 150 of FIG. 1B.

FIG. 29A depicts a cross-sectional view of the passive device 2800 ofFIG. 28A along line 2815 as a capacitor.

FIG. 29B depicts a circuit diagram of a capacitor corresponding to FIG.29A.

FIG. 30A depicts a cross-sectional view of the passive device 2819 ofFIG. 28B along line 2817 as a resistor.

FIG. 30B depicts a circuit diagram of a resistor corresponding to FIG.30A.

FIG. 31A depicts one embodiment of a passive device as a capacitorformed by a stack of alternating layers of a conductive material and adielectric material, with contacts on a first side of the stack.

FIG. 31B depicts one embodiment of a passive device as a capacitorformed by a stack of alternating layers of a conductive material and adielectric material, with contacts on opposing first and second sides ofthe stack.

FIG. 31C depicts one embodiment of a passive device as first and secondcapacitors formed by a stack of alternating layers of a conductivematerial and a dielectric material.

FIG. 31D depicts one embodiment of a passive device which includes aresistor above a capacitor, formed by a stack of alternating layers of aconductive material and a dielectric material.

FIG. 31E depicts one embodiment of a passive device as a resistor formedby a stack of alternating layers of a conductive material and adielectric material.

FIG. 31F depicts one embodiment of a passive device 3158 as tworesistors formed by a stack of alternating layers of a conductivematerial and a dielectric material.

FIG. 32A depicts a method for fabricating a passive device as acapacitor in a peripheral region of a 3D stacked non-volatile memorydevice according to the structures of FIGS. 28A to 31E, where a wet etchis performed via slits.

FIG. 32B depicts a method for fabricating a passive device as acapacitor in a peripheral region of a 3D stacked non-volatile memorydevice according to the structures of FIGS. 28A to 31E, where a wet etchis performed via holes.

FIG. 33A depicts a method for fabricating a passive device as a resistorin a peripheral region of a 3D stacked non-volatile memory deviceaccording to the structures of FIGS. 28A to 31E, where a wet etch isperformed via slits.

FIG. 33B depicts a method for fabricating a passive device as a resistorin a peripheral region of a 3D stacked non-volatile memory deviceaccording to the structures of FIGS. 28A to 31E, where a wet etch isperformed via holes.

DETAILED DESCRIPTION

A 3D stacked non-volatile memory device includes various types ofcircuitry for providing power and control signals in the device.Typically, the circuitry is provided under a stacked non-volatile memorycell array which is carried by the substrate, and in a peripheral areaof the substrate, lateral of the stacked non-volatile memory cell array.One or more lower metal layers are provided below the stackednon-volatile memory cell array, one or more upper metal layers areprovided above the stacked non-volatile memory cell array, andconnections are made between the lower and upper metal layers to routethe signals. In one aspect, techniques and structures are provided whichallow the lower and upper metal layers to be connected in aspace-efficient manner. In another aspect, passive devices such asresistors and capacitors are formed in the peripheral region in aspace-efficient manner.

FIG. 1A is a perspective view of a 3D stacked non-volatile memory device100 in which a plane of memory cells is arranged in separate subarrays.In the memory device 100, a substrate 140 carries an example plane 110of memory cells in subarrays 112, 114, 116 and 118, an example plane 120of memory cells in subarrays 122, 124, 126 and 128, and a peripheralarea 130 with peripheral regions 132 and 134 which include circuitry foruse by the subarrays. The substrate 140 can also carry circuitry underthe subarrays, along with one or more lower metal layers which arepatterned in conductive paths to carry signals of the circuitry. A planecould be associated with a common substrate region such as a p-well.

If there is no peripheral circuitry under array, there is no need toform wells in the substrate. On the other hand, if some peripheralcircuits are placed under the array, the configuration of wells shouldcorrespond to transistors and other elements in those circuits. Forinstance, NMOS transistors are typically placed in a p-well, and PMOStransistors are placed in an n-well. Some NMOS transistors can be placeddirectly in the silicon substrate, which is typically p-type. Atriple-well could also be used, e.g., a p-well placed inside an n-well,in a p-substrate. An NMOS transistor can be placed in such triple-well.An advantage of a triple-well is that the bias can be easily supplied tothe transistor body, if necessary, e.g., a p-well can be biased for anNMOS that is placed in the triple-well.

The subarrays are formed in an intermediate region 142 of the memorydevice. In an upper region 144 of the memory device, one or more uppermetal layers are patterned in conductive paths to carry signals of thecircuitry. Each subarray comprises a stacked area of memory cells, wherealternating levels of the stack represent word lines. In one possibleapproach, each subarray has opposing tiered sides from which verticalcontacts extend upward to an upper metal layer. Additionally, a gapbetween each subarray is a hook up area which allows vertical contactsto extend upward from the substrate to an upper metal layer. The gap isalso a word line transfer area which allows word line segments indifferent subarrays to be connected. The space in the word line hookupand transfer area can also be used to carry signals from under to overarray, by high aspect ratio vias, connecting metal wiring under array tometal wiring over array. For instance, if sense amplifier is placedunder array, the space can be used to carry power signals, such asVDDSA, SRCGND (source ground), VSS and so forth.

The one or more lower metal layers extend at a height which is below aheight of a bottom layer of each subarray, and the one or more uppermetal layers extend at a height which is above a height of a top layerof each subarray.

In one possible approach, the length of the plane, in the x-direction,represents a direction in which signal paths to word lines extend in theone or more upper metal layers, and the width of the plane, in they-direction, represents a direction in which bit lines extend in the oneor more upper metal layers. Source lines may also extend in thex-direction. The z-direction represents a height of the memory device100.

A drawback of this approach is the space on the memory device which isconsumed between subarrays.

FIG. 1B is a perspective view of a 3D stacked non-volatile memory device150 in which a plane of memory cells is arranged in contiguoussubarrays. In the memory device 150, a substrate 190 carries an exampleplane 170 of memory cells which can include undivided subarrays, 172,174, 176 and 178, for instance, where space is saved due to the lack ofgaps between subarrays. A subarray can be a portion of a memory arraywhich uses common circuitry and/or control or power signals. In oneapproach, multiple subarrays in a plane have common word line signals,but have different sets of bit line and sense amplifier signals. A planecould alternatively have only one subarray.

Alternatively, divided subarrays as in FIG. 1A can be used with thetechniques described herein. One reason to divide a plane into subarraysis to reduce capacitive loading, since a very long word line can have ahigh capacitance, resulting in higher capacitive loading and RC delay.Divided subarrays also provide gaps as mentioned for connections fromunder to over array, which can be used in addition to the interconnectsand other structures discussed herein.

In another approach, the plane 170 does not include subarrays, butincludes a stack of cells which use common circuitry and/or control orpower signals. Similarly, an example plane 160 of memory cells includessubarrays 162, 164, 166 and 168. A peripheral area 180 includesperipheral regions 182 and 184. In practice, peripheral regions canextend on one or more sides of a 3D stacked memory array which comprisesone or more planes such as planes 160 and 170. For simplicity, theperipheral area 180 is depicted on one side of the 3D stacked memoryarray.

The planes are formed in an intermediate region 192 of the memorydevice. In an upper region 194 of the memory device, one or more uppermetal layers are patterned in conductive paths to carry signals of thecircuitry. The upper and lower metal layers may be considered to bewiring layers. In one possible approach, each plane, rather than eachsubarray, has opposing tiered sides from which vertical contacts extendupward to an upper metal layer. There is no gap between subarrays whichallows vertical contacts to extend upward from the substrate to an uppermetal layer. Instead, one or more conductive interconnects are providedas described herein which provide an electrical connection between theone or more lower metal layers and the one or more upper metal layers.The conductive interconnects are fabricated in the stack or plane itselfto connect circuitry in the substrate 190 to signal lines in the one ormore upper metal layers.

Each array can further include one or more blocks, which are portions ofthe array arranged laterally of one another, e.g., in the bit linedirection (y-direction). The blocks are insulated from one another byinsulation-filled dividers/slits. For example, array 160 includes blocks161 and 163 separated by divider 165, and array 170 includes blocks 181and 183 separated by divider 185.

FIG. 2A depicts a top view of the 3D stacked non-volatile memory device100 of FIG. 1A. Like-numbered elements correspond to one another in thedifferent figures. Each subarray can include sense amplifier circuitry,for instance, which is used for read and verify operations of the memorycells in the subarray. The sense amplifier circuitry can include, e.g.,latches, processing circuitry and bit line hookups. The sense amplifiercircuitry can provide signals such as Vdd, source ground and Vss. In oneapproach, the sense amplifier circuitry is provided on opposing sides ofeach subarray, in a double-sided configuration. For example, in theplane 120, subarrays 122, 124, 126 and 128 include sense amplifiercircuitry 240 and 241; 242 and 243; 244 and 245; and 246 and 247,respectively.

The plane 120 can include column circuitry 260 as well, which is underthe subarray 124 in this example. Regions 202, 204, 206, 208 and 210 arehook up areas where contacts can be fabricated to extend upward to theone or more metal layers, for instance. For example, a lower metal layersuch as M0 can be connected to an upper metal layer such as D2. In oneapproach, of the lower metal layers, M0 is below M1, and of the uppermetal layers, D0 is below D1 and D1 is below D2. Regions 204, 206 and208 are also word line transfer areas in which signal paths for wordlines can be joined among the different subarrays. In this approach, aset of word lines extends in segments across the subarrays, with wordline hook-up and transfer areas between the subarrays.

One advantage of separating the plane into subarrays is to providegreater flexibility to configure power busses/connections for senseamplifiers.

These regions are also gaps between the subarrays. In the peripheralarea 130, a region 212 may be used for providing vertical contactstructures between a source line driver in the substrate andcorresponding signals paths in the one or more upper metal layers. Aregion 214 may be used for providing vertical contact structures betweenrow and column core drivers and corresponding signals paths in the oneor more upper metal layers. The row and column core drivers may providesignals, e.g., for source ground and a bit line driver. The region 132may include other circuitry, e.g., for use by the plane 120.

Similarly, in the plane 110, subarrays 112, 114, 116 and 118 includesense amplifier circuitry 250 and 251; 252 and 253; 254 and 255; and 256and 257, respectively. The plane 110 can include column circuitry 262 aswell, which is under the subarray 114 in this example. Regions 222, 224,226, 228 and 230 are hook up areas where contacts can be fabricated toextend upward to the one or more metal layers, for instance. Regions224, 226 and 228 are also word line transfer areas in which signal pathsfor word lines can be joined between the different subarrays. Theseregions are also gaps between the subarrays.

In the peripheral area 130, a region 232 may be used for providingvertical contact structures between a source line driver in thesubstrate and corresponding signals paths in the one or more upper metallayers. A region 234 may be used for providing vertical contactstructures between row and column core drivers and corresponding signalspaths in the one or more upper metal layers. The region 134 may includeother circuitry, e.g., for use by the plane 110. The regions 204, 206and 208, and 224, 226 and 228 may consume about 10% of the area of theoverall memory array area. The memory array may include, e.g., the setof one or more arrays on the memory device chip.

Although some circuitry is provided directly under the plane andsubarrays, a significant amount of circuitry is provided in a peripheralregion. This circuitry includes high voltage transistors. The area ofthe substrate directly under the plane and subarrays has not been usedfor this circuitry due to the difficulty in making power connections tothe upper metal layers. These problems are addressed by an interconnectas described herein.

FIG. 2B depicts a top view of the 3D stacked non-volatile memory device150 of FIG. 1B. The memory device 150 differs from the memory device 100in that the regions 204, 206 and 208, and 224, 226 and 228 are notpresent, so that the area consumed by the memory device is reduced.Further, in the plane 170, an in-plane interconnect area 261 is providedwhich extends along a length of the plane, and can be located midwayacross the y-direction width of the plane or otherwise in the plane 170,e.g., intermediate to the edges of the plane, or at the edge of theplane. Similarly, in the plane 160, an interconnect area 263 is providedwhich extends along a length of the plane.

FIG. 3 depicts a top view of one embodiment of the plane 170 of the 3Dstacked non-volatile memory device 150 of FIG. 1B, showing at least oneinterconnect area IA1 having two interconnects I1 and I2 (e.g.,interconnect structures) and at least one cell area (memory cell areasCA1 and CA2 at left and right hand portions, respectively, of the plane)having four subarray regions 172, 174, 176 and 178. The twointerconnects I1 and I2 can comprise a conductive material such as metalsilicide, and are separated from one another by an insulation-filledslit S6. In one approach, the interconnects essentially consist of metalsilicide. The interconnect I1 is separated from the cell area CA1 by aninsulation-filled slit S5, and the interconnect I2 is separated from thecell area CA2 by an insulation-filled slit S7. An example contactstructure C1, e.g., a contact plug, touches and extends upward from theinterconnect I1 at a top surface of the interconnect area I1 which isnot at a terraced or stepped portion of the interconnect area IA1. Incontrast, an example contact structure C2 touches and extends upwardfrom the interconnect I1 at the terraced portion of the interconnectarea IA1. The contact structure can comprise, e.g., metal or anotherconductive material such as heavily doped polysilicon (poly).

If adjacent interconnects, e.g., I1 and I2, are biased differently, theapplicable potential difference between them can be accounted for in thechoice of the width of the insulation filled slit S6 used to separatethem, to control leakage between them, and/or prevent dielectricbreakdown. That is, the higher the potential difference between adjacentinterconnects, the greater the width (w) of the slit. Thus, one of theinsulation-filled slits of the at least one interconnect area has awidth based on, e.g., in proportion to, a potential difference betweenadjacent metal silicide interconnects in the at least one interconnectarea. The potential or voltage difference refers to a differencebetween: a voltage across one of the metal silicide interconnects, and avoltage across another, adjacent metal silicide interconnect. Thevoltage across one of the metal silicide interconnects may be adifference between a potential at an upper metal layer which contactsthe interconnect and a potential at a lower metal layer which contactsthe interconnect.

The contact structures can be placed in any convenient location on aninterconnect, and can be created using a contact mask. The contactstructures can comprise metal, for instance, and can extend upward fromthe interconnects to the one or more upper metal layers. To controlcontact resistance, and improve contact yield, one or more contacts suchas C1 can be placed on top of an interconnect, e.g., on the flat surfaceof the interconnect which is not part of the tiered portion of thearray, and/or one or more contacts such as C2 can be used.

Bottom portions of the interconnects can be connected to one or morelower metal layers by an appropriate contact structure, as discussedfurther below. Multiple interconnects can be provided which are adjacentto one another, as shown here, or non-adjacent.

The interconnect allows elimination of the transfer and hook-up areasbetween subarrays by providing a different and effective way for senseamplifier and power connections to be made to an upper metal layer. Theinterconnect is a “string” of multiple layer word lines that forms a“poly stack wire” placed, e.g., in the middle of a plane, e.g., partwayacross the plane, separating the plane into at least two regions, or inother areas of the chip. In one embodiment, the interconnect is formedusing word line plates and in-between poly plates intrinsicallyconnected by silicidation, thus forming and reducing the resistance ofthe effective multi-layer word line stack wire. The bottom of theinterconnect is connected to under-array metal layers such as M1. Thus,the interconnect allows immediate connection to under the array. As anadditional benefit, it allows placing high-voltage transistor circuitrywith a large number of high-voltage transistors (e.g. for cell sourcedischarge, charge pumps, etc.) directly under the array, thus reducingthe required peripheral area.

It is also possible to connect multiple interconnects in parallel tofurther reduce resistance.

The slits can be from about tens to hundreds of nanometers in width, forinstance and spaced apart by an equal or greater distance than thewidth, in one approach. Each slit can run the full length and height ofthe plane. The slits can be formed periodically and uniformly across thewidth of the plane. For interconnects, their width and frequency ofplacement can be different. Their size and density should satisfylithography (and printability) requirements, etch capabilities, and soforth.

The plane is a stacked structure which includes alternating layers L0 toL13 of a conductive material and a dielectric material. For example,layers L1, L3, L5, L7, L9, L11 and L13 can be layers of a conductivematerial, and layers L0, L2, L4, L6, L8, L10, L12 and L14 (shown furtherbelow) can be layers of a dielectric material. An additional conductivelayer L15 and dielectric layer L16 can also be used. L0 and L16 can beconsidered to be bottom and top layers of the stack, although additionallayers could be provided. Further, in this example, the cell areas CA1and CA2 have corresponding slit patterns. A slit refers, e.g., to a voidwhich extends vertically in the stack of the plane, typically from anetch stop layer at the bottom to at least a top layer of the stack. Theslit can extend down to the etch stop layer. The slit can be filled withinsulation in the completed memory device. A slit can have a generallyuniform cross-section or a varying cross-section, such as across-section which is wider at the top than the bottom. The slitpattern of cell area CA1 includes parallel slits 306 and 307, and theslit pattern of cell area CA2 includes parallel slits 326 and 327.Essentially, a single continuous slit extends in a zig-zag or combpattern in each cell area so that the stack is divided into two portionsin each cell area. For example, layer L13A-L represents a first portionof the left hand cell area CA1, layer L13B-L represents a second portionof the left hand cell area CA1, layer L13A-R represents a first portionof the right hand cell area CA2, and layer L13B-R represents a secondportion of the right hand cell area CA2. This approach provides greaterflexibility in controlling the memory cells.

Slits and holes are examples of voids.

Each cell area includes rows of columnar, e.g., vertical, memory holes.The memory holes extend vertically and include memory cells such as in avertical NAND string. For example, cell area CA1 includes rows 301 to305 of memory holes, and cell area CA2 includes rows 321 to 325 ofmemory holes. Each hole is represented by a circle. The memory holes canbe arranged in the different subarrays 172, 174, 176 and 178, forinstance. Due to the slit patterns, the rows 301, 302 and 305 are incontact with the layer L13A-L, the rows 303 and 304 are in contact withthe layer L13B-L, the rows 321, 324 and 325 are in contact with thelayer L13A-R, and the rows 322 and 323 are in contact with the layerL13A-L.

Each column of holes can be separated by a slit, e.g., the slit isplaced between memory holes belonging to the same NAND or BiCS string,and between memory holes of adjacent strings, such as in FIG. 5. In oneapproach (see FIGS. 3 and 4), the slit is placed between memory holes ofthe same string, but not between memory holes of adjacent strings. Thememory strings in the cell area CA1 can belong to one block while thememory strings in the cell area CA2 belong to another block. Each cellarea can have separate connections in a hook up region. With a comb-likeslit pattern, as shown, each block connection can be made on opposingsides (top and bottom) of a block. For example, for 25 layers of wordline, there can be 25 connections in a top hook up region 25 in a bottomhook up region. As an example, a block can have, e.g., 8, 12 or 16memory strings. Additionally, connections can be provided for selectgate transistors and back gates.

The figure represents a simplification, as many more rows of memoryholes will typically be used, extending to the right and left in thefigure. Also, the figures are not necessarily to scale. The width of theat least one interconnect area can be relatively very small compared toa width of the plane.

FIG. 4 depicts a top view of a plane 470 of the 3D stacked non-volatilememory device 150 of FIG. 1B, showing at least one interconnect area IA2having eight interconnects I3 to I10, and at least one cell area (CA1and CA2) having four subarray regions. Here, insulation-filled slits411, 412 and 413 extend parallel to one another in the x-direction,while in the transverse y-direction, insulation-filled slits 414, 415,416 and 417 extend parallel to one another. This grid ofinsulation-filled slits results in the eight interconnects which areelectrically isolated from one another and can therefore serve asseparate conductive paths from below to above the stack. Examplecontacts structures C3 to C10 are provided for the interconnects I3 toI10, respectively.

The slits 411 and 412 are a pair of parallel insulation-filled slits andthe slit 414 is at least one transverse insulation-filled slit whichextends transversely to the pair of parallel insulation-filled slits. Atleast one metal silicide interconnect comprises one region 13 of metalsilicide on one side of the at least one transverse insulation-filledslit, and another region 15 of metal silicide on another side of the atleast one transverse insulation-filled slit. The one region of metalsilicide on the one side of the at least one transverseinsulation-filled slit and the another region of metal silicide on theanother side of the at least one transverse insulation-filled slit,connect respective contact structures C3 and C5 of at least one lowermetal layer M0, M1 to respective portions of the at least one uppermetal layer. See FIG. 23C for a cross-sectional view along line 440.

There can be one or multiple interconnects extending vertically in thearray, and one or multiple contacts can be provided for eachinterconnect.

FIG. 5 depicts a top view of one embodiment of a plane 570 of the 3Dstacked non-volatile memory device 150 of FIG. 1B, showing at least oneinterconnect area IA1 having two interconnects I1 and I2 and at leastone cell area (cell areas CA3 and CA4). This arrangement is similar tothat of FIG. 3 except that one subarray of memory holes is provided. Thememory holes are provided in rows 501 to 505 in the cell area CA3, andin rows 521 to 525 in the cell area CA4. The slit pattern in the cellarea CA3 includes slits 51 to S4, and the slit pattern in the cell areaCA4 includes slits S7 to S10.

Note that the memory holes can be in a regular grid, or the rows can beoffset relative to one another, e.g., in the x direction. In onapproach, the at least one interconnect area does not comprise verticalcolumns of NAND cells, or any memory cells.

A cross-sectional view of the plane 570 along line 550 is provided inFIG. 8. This cross-section includes example memory holes H1 to H4 in CA3and H5 to H8 in CA4. A cross-sectional view of the plane 570 along line580 is provided in FIG. 22A. This cross-section includes a portion ofthe cell area CA3 which does not include memory holes. A cross-sectionalview of the interconnect I1 of the plane 570 along line 590 is providedin FIG. 23A.

In the slit pattern of FIG. 4, a slit is provided between every two rowsof memory holes. In the slit pattern of FIG. 5, a slit is providedbetween every row of memory holes. In one approach, pairs of memoryholes and their vertical columns of memory cells are joined, such as ina U-shaped NAND string configuration, and bisected by a slit. Forexample, memory holes H1 and H2 may each contain a vertical column ofmemory cells, where the vertical columns of memory cells are connectedby a back gate below the stack, and bisected by S2. The slit S2insulates the word line layers which include memory holes H1 and H2 fromeach other so that they may be separately controlled by their respectiveword line plates, e.g., L13B-L can provide control signals to a controlgate of a memory cell associated with the memory hole H1, and L13A-L canprovide control signals to a control gate of a memory cell associatedwith the memory hole H2. A slit thus can bisect rows of memory holeswhich are the two branches or legs of U-shaped NAND strings. In anothercase, a slit is provided between rows of memory holes of straight NANDstrings. The slit pattern extends to each layer of the stack.

FIG. 6 depicts a method for fabricating a 3D stacked non-volatile memorydevice according to the structures of FIGS. 8-14B, where a wet etch isperformed via slits. The steps include: Provide below-stack circuitryand metal layers on substrate, 600 (FIG. 8); Provide etch stop layerwith back gate, 602 (FIG. 8); Provide at least one contact structure tobelow-stack metal layer through etch stop layer, 604 (FIG. 8); Depositalternating undoped/lightly doped and heavily doped polysilicon layers,606 (FIG. 8); Etch slits in the at least one cell area and in the atleast one interconnect area using a common mask, 608 (FIG. 8); Fill inthe slits in the at least one interconnect area with insulation (or maskthe slits), 610 (FIG. 8); Etch memory holes in the at least one cellarea, 612 (FIG. 8) (this can be a reactive ion etch in the cell areasusing a memory hole mask which protects the interconnect area); Fill inthe memory holes with insulation, 614 (FIG. 8); Perform a wet etch viathe slits in the at least one cell area, to remove portions of theundoped/lightly doped polysilicon layers in the at least one cell area,but not portions of the undoped/lightly doped polysilicon layers in theat least one interconnect area, 616 (FIG. 9); Deposit insulation (e.g.,one or more layers) in the recesses via the slits in the at least onecell area, 618 (FIG. 10); Clean out the slits in the at least one cellarea and in the at least one interconnect area (or unmask the slits inthe at least one interconnect area), 620 (FIGS. 10 and 11); Performsilicidation of: (a) the portions of the heavily doped polysiliconlayers in the at least one cell area, and (b) the portions of theheavily doped and undoped/lightly doped polysilicon layers which are inthe at least one interconnect area, 622 (FIG. 12); Deposit insulation inthe slits in the at least one interconnect area, 624 (FIG. 13); Cleanout the memory holes, 626 (FIG. 13); Fill in memory holes withoxide-nitride-oxide (ONO), polysilicon layer and core filler, 628 (FIG.14); and Provide above-stack metal layers and connect the at least oneinterconnect area to the above-stack metal layer by at least one contactstructure, 630 (FIGS. 23A, 23B and 24).

In this scheme, “wet etch through slits”—memory holes initially filledin with dielectric serve as anchors to the highly doped poly layersafter portions of the undoped/lightly doped poly layers are removed.

The steps need not necessarily be performed as discrete steps in theorder indicated. For example, the etching steps can be performedconcurrently, at least in part. Various modifications can be made.Moreover, other steps which are known from the art of semiconductorfabrication but are not explicitly depicted here may also be performed.

Undoped or lightly doped poly may have a doping concentration of 10^15to 10^17 cm-3 or less, for instance. 10^15 means 10 raised to the powerof 15. The term “undoped/lightly doped polysilicon” or the like denotespolysilicon which is undoped or relatively lightly doped. The term“heavily doped polysilicon” or the like denotes polysilicon which isrelatively highly doped. An example of heavily doped poly is p-typedoped poly with a doping concentration of 10^20 to 10^21 cm-3 or more.An example ratio of doping concentrations for the heavily doped poly tothe lightly doped poly is therefore 10^3 (10^20/10^17) to 10^6(10^21/10^15). An example p-type dopant is Boron. High doping isdesirable for less word line resistance, and for better silicidation.The sheet resistance of heavily doped poly is about 500-1000 ohm/square,for instance. The sheet resistance of a partially silicided poly layerin a 3D stack is about 20-100 ohm/square—about ten times lower than forunsilicided heavily doped poly.

Undoped poly is an insulator but is not highly insulating. Pure orundoped poly has a resistivity of at least about 10 kilo-ohm·cm. Lightlydoped or p type poly has a resistivity of about 1-10 ohm·cm. Highlydoped or p+ type poly has a resistivity of about 0.01 ohm·cm or less. Aninsulator is a material with low conductivity. A dielectric is a type ofinsulator which can be polarized by an applied electric field. Thepolarizability is expressed by the dielectric constant. SiO2, SiN, or acombination of SiO2 and SiN, are examples of insulators which are alsodielectrics. Generally, oxide, nitride or a combination of oxide andnitride are examples of dielectrics. Highly doped poly or metal silicideis considered to be a conductive material while undoped/lightly dopedpoly or a dielectric such as oxide, nitride or a combination of oxideand nitride is not.

FIG. 7 depicts a method for fabricating a 3D stacked non-volatile memorydevice, corresponding to the structures of FIGS. 15-21A, where a wetetch is performed via memory holes. The steps include: Providebelow-stack circuitry and metal layers on substrate, 700 (FIG. 16);Provide etch stop layer with bottom gate, 702 (FIG. 16); Provide atleast one contact structure to below-stack metal layer through etch stoplayer, 704 (FIG. 16); Deposit alternating undoped/lightly doped andheavily doped polysilicon layers, 706 (FIG. 16); Etch slits in the atleast one cell area and in the at least one interconnect area using acommon mask, 708 (FIG. 16); Fill in the slits in the at least one cellarea and in the at least one interconnect area with insulation (or maskthe slits in the at least one interconnect area), 710 (FIG. 16); Etchmemory holes in the at least one cell area, 712 (FIG. 16); Perform a wetetch via the memory holes in the at least one cell area, to removeportions of the undoped/lightly doped polysilicon layers in the at leastone cell area, 714 (FIG. 17); Deposit ONO layers (as a dielectric orinsulation) in the memory holes in the at least one cell area and in therecesses, 716 (FIG. 18); Clean out the slits in the at least one cellarea and in the at least one interconnect area (or unmask the slits inthe at least one interconnect area), 718 (FIG. 19); Perform silicidationof: (a) the portions of the heavily doped polysilicon layers in the atleast one cell area, via the slits in the at least one cell area and (b)the portions of the heavily doped and undoped/lightly doped polysiliconlayers in the at least one interconnect area, via the slits in the atleast one interconnect area 720 (FIG. 20A); Deposit insulation in theslits in the at least one cell area and in the at least one interconnectarea, 722 (FIG. 20B); and Provide above-stack metal layers and connectthe at least one interconnect area to the above-stack metal layer by atleast one contact structure, 724 (FIGS. 23A, 23B and 24).

The steps need not necessarily be performed as discrete steps in theorder indicated. For example, the etching steps can be performedconcurrently, at least in part. Various modifications can be made.Moreover, other steps which are known from the art of semiconductorfabrication but are not explicitly depicted here may also be performed.

Note in in the above-mentioned processes (e.g., FIGS. 6 and 7), there isan option to deposit the dielectric between the heavily doped polylayers via the memory hole instead of via slits. However, additionalcleaning is needed to remove the dielectric, which adheres to the memoryhole walls, increasing costs. FIGS. 8 to 14B depict stages of oneembodiment of fabrication of a layered semiconductor device which resultin a 3D stacked non-volatile memory device as described in the processflowchart of FIG. 6. This process involves a wet etch via slits. Incontrast, the process of FIG. 7 involves a wet etch via memory holes.

FIG. 8 depicts a layered semiconductor material 800 which is consistentwith a cross-sectional view of the region 530 of the 3D stackednon-volatile memory device of FIG. 5 along the line 550, showing slitsS1 to S4 and S8 to S10 and memory holes H1 to H8 in the cell areas CA3and CA4, and slits S5 to S7 in the interconnect area IA1. At least oneinterconnect area IA1 is lateral of at least one cell area in the array.A slit can be a trench which may have various widths. Note that there isanother mask that can define wider trenches than those used for theslits in the array. These (the mask and trench itself) are used, e.g.,to separate the peripheral and array regions. In defining areas forpassive devices, both can be used as applicable.

The substrate region 190 includes a semiconductor substrate such as asilicon wafer, a layer 852 in which source/drain regions 864 and 866 ofa transistor gate 862 can be formed, a layer 854 which includes thetransistor gate 862 and lower metal layers M0 and M1, and an etch stoplayer 856 which has a composition based on the process scheme. Forexample, the etch stop layer can be SiO2 or nitride. The patterned backgate is used for the pipe connection of each string.

M0 can be used, e.g., for power line and global control signals, and M1can be used, e.g., for bit line and bus signals. Other uses of M0 and M1are provided herein as well.

The transistor gate 862 and source/drain regions 864 and 866 are part ofan example transistor 860, which is an example of circuitry in thesubstrate which can be connected to one or more upper metal layers by anin-plane interconnect. Terminals of the circuitry 860 are connected bycontact structures to portions of the M0 layer. For example, a contactstructure 868 connects the source/drain region 866 to a portion of M0, acontact structure 870 connects the portion of M0 to a portion of M1, anda contact structure 872 extends upward through the etch stop layer 856to connect the portion of M1 to L0 in the interconnect area IA1. Acontact mark can be used to provide the contact structure 872.Generally, there can be one or more contacts to the bottom of one ormore interconnects.

The circuitry 860 is directly below the stack, e.g., it is under thestack and within a foot print or perimeter of the stack.

The metal layers can be fabricated from a patterned metal film. Forexample, Aluminum can be used for the top metal layer, while the otherlayers are Tungsten. Potentially, Cu can be used instead of Al for upperlayer, using a corresponding integration scheme. For silicidation, Ni,Ti, Co or W can used, for instance.

After the etch stop layer 856 is deposited, back gates 840, 842, 844 and846 are provided in the etch stop layer, for instance, to join verticalcolumns of memory cells in a U-shaped NAND configuration. In particular,trenches are provided in portions of the layer 856 below pairs ofcolumns of memory cells of a U-shaped NAND string. Layers of materialswhich are provided in the columns to form the memory cells are alsoprovided in the trenches, and the remaining space in the trenches isfilled with a semiconductor material to provide the back gates asconductive regions which connect the columns. The back gate thusconnects the two columns of each U-shaped NAND string. Each NAND stringhas its own back gate which serves to control conductivity of thestring. The layer 856 is separated (by etch) for each string. A contactto the back gate is provided in a word line hook up area, where the backgate is the lowest contact, since the back gate poly is below the wordline poly stack. The slits generally do not extend down to touch theback gates. Also, the slits are placed not only between memory holes ofthe same NAND string, e.g., slits S2, S4, S7 and S9, but also betweenmemory holes of adjacent NAND strings, e.g., slits S1, S3, S8 and S10.

Alternating layers of undoped/lightly doped and heavily dopedpolysilicon, for example, are provided as layers L0 to L16. This exampleresults in vertical columns of six memory cells, where the heavily dopedpolysilicon layers are provided at L3, L5, L7, L9, L11 and L13 ascontrol gates, at L1 as a lower select gate and at L15 as an upperselect gate. This is an example, as fewer or more layers can be used. L1is a bottom layer of doped heavily doped polysilicon. Since L1 and L15are taller than the other heavily doped polysilicon layers in thisexample, the lower and upper select gates will be taller than the memorycell control gates. In one approach, the doping of the polysiliconlayers is performed in situ. For example, undoped/lightly dopedpolysilicon for L0 is deposited (optionally while being lightly doped insitu), then polysilicon for L1 is deposited while being heavily doped,e.g., using p-type Boron, then undoped/lightly doped polysilicon for L2is deposited, then polysilicon for L3 is deposited while being heavilydoped, and so forth. L1, L3, L5, L7, L9, L11, L13 and L15 are theheavily doped layers, and L0, L2, L4, L6, L8, L10, L12, L14 and L16 arethe undoped/lightly doped layers.

After the layers of undoped/lightly doped and doped polysilicon aredeposited, the slits and memory holes are fabricated. The order offabrication can vary. In one approach, slits are etched in the cellareas CA3 and CA4 and in the interconnect area IA1. For example, slitsS1 to S3 can be etched in the cell area CA3, slits S5 to S7 can beetched in the interconnect area CA3, and slits S7 to S10 can be etchedin the cell area CA4. Advantageously, the slits can be etchedconcurrently, using a common mask which covers the stack. Reactive ionetching can be used. Further, the pattern of slits in the interconnectarea can correspond to, e.g., be the same as, the pattern of slits inthe cell areas. The widths of the slits can be the same or different inthe interconnect area and the cell areas.

To provide the memory holes in the cell areas CA3 and CA4 but not in theinterconnect area IA1, the interconnect area can be masked while etchingthe memory holes, e.g., using reactive ion etching. Memory holes H1 toH4 can be formed in the cell area CA3, and memory holes H5 to H8 can beformed in the cell area CA4. Also, in the layered semiconductor material800: a region 814 is between and adjacent to the memory hole H4 and theslit S5, a region 816 is between and adjacent to the slits S5 and S6, aregion 818 is between and adjacent to the slits S6 and S7, and a region820 is between and adjacent to the slit S7 and the memory hole H5.

Once the slits in the interconnect area are etched, they can be filledin with insulation, as indicated by the shading. Example insulationincludes a dielectric material such as SiO2, or a combination ofdielectrics, e.g. SiO2, SiN, and so forth. Alternatively oradditionally, the slits in the interconnect area are protected by amasking material such as photoresist or silicon nitride. A goal is toprotect the slits in the interconnect area to prevent a liquid etchantfrom entering the slits and removing portions of the undoped/lightlydoped polysilicon layers in the interconnect area in a subsequent wetetch process.

FIG. 9 depicts a layered semiconductor material 900 which is obtainedfrom the layered semiconductor material 800 after performing a wet etchvia the slits in the cell areas. The wet etch can involve introducing anetchant via the slits of the at least one cell area, which has a higherselectivity for the undoped/lightly doped polysilicon layers, removingportions of the undoped/lightly doped polysilicon layers which areadjacent to the slits of the at least one cell area. For example, region950 is an example portion of the undoped/lightly doped polysilicon layerL14 which is removed in the wet etch. Selectivity indicates a ratio ofetch rates. The wet etch has a relatively higher selectivity (e.g., by afactor of 1000, or more generally, 100 or more) for the undoped/lightlydoped polysilicon relative than for the heavily doped polysilicon.

That is, the wet etch is not relatively highly selective of the heavilydoped polysilicon so that it is not substantially removed. The wet etchshould remove essentially the entire undoped/lightly doped polysiliconlayers in the cell areas, so that when the regions of the removedundoped/lightly doped polysilicon are replaced by dielectric, thedielectric will extend in substantially the entire layer in the cellareas. This ensures that the word line layers at different levels areisolated from one another and not shorted together. This appliesregardless of the wet etch method, e.g., whether the etchant isintroduced via the slits, memory holes, other holes or voids, orcombinations thereof. The insulation-filled slits serve as anchors whichsupport the heavily doped poly layers when the undoped/lightly dopedpoly is removed. On the other hand, the masked interconnect area isprotected from the wet etch.

The silicidation of the doped poly layers in the cell area orinterconnect area can result in essentially all, or a large portion, ofthe doped poly in the respective area being transformed to metalsilicide. A word line layer which is partly metal silicide and partlydoped poly will still function as a conductive layer. In fact, theresistance of partly silicided word line layer will be mostly determinedby its silicided part with lower resistance

In the array area, the memory holes are placed densely. A minimumdensity of memory holes allows essentially all undoped/lightly dopedpoly in the cell areas to be removed when a wet etch is performed viathe memory holes. For example, the memory holes can have a width of60-75 nm, a pitch of about 110-125 nm in the word line or x-direction,and a pitch of about 150-165 nm in the bit line or y-direction. Theslits can have a width of about 40-50 nm. In other areas, such as theword line hook areas at opposing ends of the array, essentially all ofthe undoped/lightly doped poly can be removed as well in a wet etch. Inthose areas, memory holes need not be provided. However, holes referredto as replacement (or inactive) holes may be used to removeundoped/lightly doped poly. These holes can be arranged with a similardensity as in the array.

The term “hole” or “columnar hole” or the like as used herein is meantto include a memory hole, replacement hole or similarvertically-extending columnar void which can be filled while still berecognizable as a hole.

For a 3D capacitor or 3D resistor, discussed further below, a sufficientdensity of holes may be used to remove undoped/lightly doped poly. For a3D resistor, the hole density can be the same as in the array, since ahigh density of memory holes will desirably increase the resistance ofthe poly layers. For a 3D capacitor, a minimum hole density is desiredwhich is still sufficiently high to remove the undoped/lightly dopedpoly. A lower density of holes desirably increases the effective area ofcapacitor plates, therefore increasing the capacitance of each layer.The optimal hole densities can be found by experimentation.

FIG. 10 depicts a layered semiconductor material 1000 which is obtainedfrom the layered semiconductor material 900 after filling in voids withinsulation via the slits in the cell areas CA3 and CA4. Insulation isprovided in the slits to fill the recesses (e.g., region 1050) whichwere created by the wet etch, as indicated by the shading. Theinsulation can be a dielectric material which insulates the word linelayers from one another. The insulator, which is deposited via the slitswith the intention to fill in the voids between the layers of heavilydoped poly will inevitably be deposited somewhat on the sidewalls of theslits. The slits in the cell area can be cleaned out to remove thesesdeposits. This can occur with the cleaning out of the slits in theinterconnect area, or separately. See FIG. 14A for further details,showing regions 1494 and 1496 of dielectric which are deposited on thesidewalls of the slit S2, and a region 1495 of insulation which is laterdeposited to fill the slit S2.

In this scheme, slits are used to fill in voids between poly withinsulation. Then, the slits are cleaned out (opened) beforesilicidation. Otherwise, the insulator on the sidewalls can preventmetal (e.g., Ni) from being deposited on poly, thereby preventingsilicidation.

In one option, the slits in the interconnect area are already filledwith insulation. In another option, the slits in the interconnect areaare voids which were protected by a masking material, in which case themasking material is removed and the slits in the interconnect area canbe left as voids. A goal is to introduce a dielectric in the recessesthroughout the entire cell array areas which is not affected by asubsequent silicidation process. The dielectric material can comprise,e.g., oxide, nitride and/or combination of oxide and nitride.

FIG. 11 depicts a layered semiconductor material 1100 which is obtainedfrom the layered semiconductor material 1000 after cleaning out theslits in the interconnect area IA1. The cleaning out of the slits can beachieved by etching such as reactive ion etching, for example. A goal isto create a narrow trench to perform silicidation in the interconnectarea IA1. The slits in the cell areas CA3 and CA4 could optionally becleaned out as well.

FIG. 12 depicts a layered semiconductor material 1200 which is obtainedfrom the layered semiconductor material 1100 after performingsilicidation via the slits in the cell areas CA3 and CA4, and via theslits in the interconnect area IA1. Silicidation is an annealing processresulting in the formation of metal-Si alloy (silicide) from the heavilydoped poly (e.g., region 1250). For example, it can include depositing ametal such as Ni, Ti, Co or W in the slits in the cell area followed byannealing which transforms the affects portions of the heavily dopedpolysilicon layers to a metal silicide. Chemical vapor deposition (CVD)or atomic layer deposition (ALD) could be used to deposit the metal. Asilicide is an alloy of silicon and metal and has the advantage ofreduced resistivity compared to heavily doped polysilicon. Thesilicidation results in metal silicide regions in place of heavily dopedpoly regions in the cell area. Additionally, since the undoped/lightlydoped polysilicon layers were not removed in the interconnect area, boththe heavily doped and undoped/lightly doped polysilicon layers in theinterconnect area are intrinsically connected by the silicidation andtransformed to a monolithic block of metal silicide which serves as aninterconnect between one or more lower metal layers and one or moreupper metal layers. In particular, regions 816 and 818 are transformedto metal silicide interconnects I1 and I2. In one approach, the metalsilicide interconnects I1 and I2 extend a height of the stack, from theetch stop layer 856 or a bottommost layer (L0) of the stack to a topmostlayer (L16) of the stack.

FIG. 13 depicts a layered semiconductor material 1300 which is obtainedfrom the layered semiconductor material 1200 after cleaning out thememory holes in the cell areas CA3 and CA4. The slits S5, S6 and S7 inthe interconnect area are filled in with insulation. The memory holes H1to H8 in the cell area are cleaned out, e.g., by etching. The slits canbe protected from the etching. Additionally, the drain-side memory holesH1, H4, H5 and H8 are extended up to a bit line BL, the source-sidememory holes H2 and H3 are extended up to a select line SL1, and thesource-side memory holes H6 and H7 are extended up to a select line SL2.The memory holes are filled with a number of layers as detailed in FIGS.14A and 14B.

FIG. 14A depicts a layered semiconductor material 1400 which is obtainedfrom the layered semiconductor material 1350 after filling in the memoryholes. In one approach, the memory holes H1 and H2 are filled in bydepositing ONO and polysilicon layers on sidewalls of the columnarmemory holes, e.g., using ALD. For example, a block or back oxide can bedeposited as layer 1450 in memory hole H1, and as layer 1460 in memoryhole H2. Next, a nitride such as SiN as a charge trapping layer can bedeposited as layer 1451 in memory hole H1, and as layer 1461 in memoryhole H2. Next, a tunnel oxide can be deposited as layer 1452 in memoryhole H1, and as layer 1462 in memory hole H2. Next, a polysilicon bodycan be deposited as layer 1453 in memory hole H1, and as layer 1463 inmemory hole H2. Next, a core filler dielectric can be deposited asregion 1454 in memory hole H1, and as region 1464 in memory hole H2.

The ONO layers form a dielectric stack. The stack layers can be morecomplex, such as where at least one of these layers can be a combinationof layers of oxide and nitride. If we consider the metal (M) silicide ofthe word line, and the polysilicon body (S), a MONOS stack and memorycell are formed. Alternatively, if the word line is poly (S), a SONOSstack and memory cell are formed.

An example select gate 1490 is formed by the memory hole H1 and aportion of the metal silicide layer L15 which surrounds H1, while anexample memory cell 1492 is formed by the memory hole H2 and a portionof the metal silicide layer L15 which surrounds H2. Similarly, anexample select gate 1491 is formed by H1 and a portion of L15 whichsurrounds H1, while an example memory cell 1493 is formed by H2 and aportion of L15 which surrounds H2. Additional memory cells are similarlyformed along the memory holes. Recall that L12, L14 and L6 are exampledielectric layers, and L13 and L15 are conductive (metal silicide)layers.

FIG. 14B depicts a cross-sectional view of the memory hole H1 of FIG.14A. The layers can be cylindrical, for instance. Core filler region1454 is inside the polysilicon body 1453, which is inside the tunneloxide 1452, which is inside the nitride 1451, which is inside the blockoxide. Generally, each of a tunnel layer and a blocking layer can becomprised of a stack of oxide and nitride layers to improve theirrespective properties affecting endurance and data retention.

FIGS. 15 to 21A depict stages of another embodiment of fabrication of alayered semiconductor device which result in a 3D stacked non-volatilememory device as described in the process flowchart of FIG. 7. Thisprocess involves a wet etch via memory holes.

FIG. 15 depicts a top view of another embodiment of a plane 1569 of the3D stacked non-volatile memory device 150 of FIG. 1B, showing at leastone interconnect area IA3 having six interconnects I11 to I16, and atleast one cell area (cell areas CA5 and CA6). In this slit pattern, aslit is provided between every row of memory holes in the cell arrayareas. A slit comb-like structure can be provided for the word line andselect gate hook up connections on opposing sides (top and bottom inlayout) of each block.

For example, slits S11 to S13 are provided in the cell area CA5, betweenrows 1501 to 1504 of memory holes, and slits S21 to S23 are provided inthe cell area CA6, between rows 1505 to 1508 of memory holes.Insulation-filled slits S14 to S20 are provided in the interconnect areaIA3. Contact structures C11 to C16 are provided for the interconnectsI11 to I16, respectively. A cross-sectional view of the plane 1569 alongline 1550 is provided in FIG. 16. This cross-section includes examplememory holes H11 to H13 and H14 to H17.

FIG. 16 depicts a layered semiconductor material 1600 which isconsistent with a cross-sectional view of the plane 1569 of FIG. 15along the line 1550, showing slits and memory holes in the cell areasCA5 and CA6, and slits in the interconnect area IA3. The substrateregion 190 is repeated. In this example, the vertical columns of memorycells which will be provided in the memory holes terminate at a sourceline of, e.g., n+ poly 1650. For example, straight NAND strings may befabricated in this case. While straight NAND strings are an option,U-shaped NAND strings have some advantages. Specifically, in U-shapedNAND, both select gates are on the top, one connected to a bit line, oneto a source line, and each made of metal, e.g., D1 and D2, for lowerresistance. The drain junctions (n+) for both select gate transistorscan be the same, not subjected to a MONOS anneal cycle.

The sources lines run parallel to one another in the y-direction, may bemade of n+ poly to provide a higher source line resistance, and areconnected to respective source line drivers. The contact structure 872extends upward to connect the portion of M1 to L0 in the interconnectarea 1620. The contact structure 872 can be positioned between sourcelines so that it does not contact them, and/or an insulation may be usedaround the contact structure 872 so that it does not contact the sourcelines.

The alternating layers of undoped/lightly doped and heavily dopedpolysilicon are provided as before as layers L0 to L16, except that L1is now used to provide a source-side select gate for each NAND string.L1 is shown having a slight greater height than the other layers,similar to the height of the layer L15 used for the drain-side selectgate. After the layers of undoped/lightly doped and heavily dopedpolysilicon are deposited, the slits and memory holes are fabricated. Inone approach, slits S11 to S13 can be etched in the cell area CA5, slitsS14 to S20 can be etched in the interconnect area CA3, and slits S21 toS23 can be etched in the cell area CA6. Advantageously, the slits can beetched concurrently, using a common mask which covers the stack.Reactive ion etching can be used. Further, the pattern of slits in theinterconnect area can correspond to, e.g., be the same as, the patternof slits in the cell areas. The widths of the slits can be the same ordifferent in the interconnect area and the cell areas, in one approach.

In this scheme “wet etch through memory holes”, slits are formed firstand filled in with SiO2 (in one example). Then memory holes are etched,and then wet etch is performed through memory holes. At that time, withundoped/lightly doped poly removed in cell areas, slits serve as anchorsto poly structure. Later slits are etched to remove sacrificial fillmaterial. Silicidation is done through the slits.

Specifically, to provide the memory holes in the cell areas CA5 and CA6but not in the interconnect area IA3, the interconnect area can bemasked while etching the memory holes, e.g., using reactive ion etching.Memory holes H10 to H13 can be formed in the cell area CA5, and memoryholes H14 to H17 can be formed in the cell area CA6. Also, in thelayered semiconductor material 1600: a region 1618 is between slits S14and S15, a region 1620 is between slits S15 and S16, a region 1622 isbetween slits S16 and S17, a region 1624 is between slits S17 and S18, aregion 1626 is between slits S18 and S19, and a region 1628 is betweenslits S19 and S20.

Once the slits in the interconnect area are etched, they can be filledin with insulation, as indicated by the shading in the slits.Alternatively or additionally, the slits in the interconnect area areprotected by a masking material such as photoresist or silicon nitride.A goal is to protect the slits in the interconnect area to prevent aliquid etchant from entering the slits in a subsequent wet etch process.

FIG. 17 depicts a layered semiconductor material 1700 which is obtainedfrom the layered semiconductor material 1600 after performing a wet etchvia the memory holes H10 to H13 and H14 to H17 in the cell areas CA5 andCA6. The wet etch can involve introducing an etchant via the memoryholes of the at least one cell area, which has a higher selectivity forthe undoped/lightly doped polysilicon layers, removing theundoped/lightly doped polysilicon layers. The wet etch is not relativelyhighly selective of the heavily doped polysilicon so that the heavilydoped polysilicon is not substantially removed. As in the case of thewet etch via the slits, essentially all of the undoped/lightly dopedpoly in the cell areas is removed. Region 1750 is an example region ofundoped/lightly doped poly in L13 which is removed by the wet etch.

FIG. 18 depicts a layered semiconductor material 1800 which is obtainedfrom the layered semiconductor material 1700 after filling in memoryholes and recesses between heavily doped poly layers and via the memoryholes in the cell areas CA5 and CA6. For example, an ONO stack can bedeposited into the memory holes by CVD and/or ALD, which also fills therecesses or voids between the heavily doped poly layer or word linelayers which were created by the wet etch. ONO is considered to be adielectric material. In one option, the slits in the interconnect areaare already filled with insulation. In another option, the slits in theinterconnect area are voids which were protected by a masking material,in which case the masking material is removed and the slits in theinterconnect area can be left as voids. A goal is to introduce an ONOmaterial in the recesses which is not affected by a subsequentsilicidation process.

FIG. 19 depicts a layered semiconductor material 1900 which is obtainedfrom the layered semiconductor material 1800 after cleaning out theslits in the cell areas CA5 and CA6 and the in the interconnect areaIA3. The cleaning out of the slits can be achieved by etching, forexample.

FIG. 20A depicts a layered semiconductor material 2000 which is obtainedfrom the layered semiconductor material 1900 after performingsilicidation via the slits in the cell areas CA5 and CA6 and in theinterconnect area IA3. The silicidation results in metal silicideregions (e.g., region 2050 in L13) where the heavily doped poly waspreviously present. As before, since the undoped/lightly dopedpolysilicon layers were not removed in the interconnect area, both theheavily doped and undoped/lightly doped polysilicon layers areintrinsically connected by the silicidation and transformed to amonolithic block of metal silicide which serves as an interconnectbetween one or more lower metal layers and one or more upper metallayers. In particular, regions 1618, 1620, 1622, 1624, 1626 and 1628 aretransformed to metal silicide interconnects I11, I12, I13, I14, I15 andI16 (FIG. 15), respectively. In one approach, the metal silicideinterconnects extend a height of the stack.

FIG. 20B depicts a layered semiconductor material 2080 which is obtainedfrom the layered semiconductor material 2000 after depositing insulationin the slits in S11 to S13 and S21 to S23 in the cell area CA5, slitsS14 to S20 in the interconnect area IA3 and slits S20 to S23 in the cellarea CA6. Additionally, the memory holes H10 to H16 are extended up to abit line BL which runs parallel to the source line 1650 in this example.

FIG. 21A depicts details of region 2100 in FIG. 20B. For memory holeH11, regions 2051 and 2052 are metal silicide regions at L15, andregions 2052 and 2054 are metal silicide regions at L13. For memory holeH12, regions 2055 and 2056 are metal silicide regions at L15 and regions2057 and 2058 are metal silicide regions at L13. Recall that L12, L14and L16 are the dielectric layers and L13 and L15 are the conductivelayers.

In one approach, the memory holes H11 and H12 are filled in bydepositing ONO layers. For example, in memory hole H11, a block oxidecan be deposited as layer 2150. Next, a nitride such as SiN as a chargetrapping layer can be deposited as layer 2151. Next, a tunnel oxide canbe deposited as layer 2152. Next, a polysilicon body can be deposited aslayer 2153 in memory hole H11. Next, a core filler dielectric can bedeposited as region 2154. The layers can be cylindrical, for instance,similar to FIG. 14B. Core filler region 2154 is inside the polysiliconbody 2153, which is inside the tunnel oxide 2152, which is inside thenitride 2151, which is inside the block oxide 2150.

In the memory hole H11, a select gate 2190 and example memory cell 2191are formed. Additional memory cells are similarly formed along thememory holes.

FIG. 22A depicts a cross-sectional view along line 580 of FIG. 5 of theplane 570, showing terraced portions 2250 and 2252 of the cell area CA3.For example, the terraced portions 2250 and 2252 may be at opposingfirst 2202 and second 2206 sides of the memory device 150. Anintermediate region 2204 extends between the opposing sides. The terracehas steps at transitions between L1 and L2, L3 and L4, L5 and L6, L7 andL8, L9 and L10, L11 and L12, and L13 and L14.

Note that the z-axis denotes height, where z0 is a height of a top ofthe substrate 190, z1 is a height of a top of the stack and the bottomof the upper region 194 and z2 is a height of a top of the upper region194.

FIG. 22B depicts contact structures of the terraced portion 2252 of thecell area CA3 of FIG. 22A. Contact structures 2254, 2256, 2258, 2260,2262, 2264 and 2266 extend upward from L1, L3, L5, L7, L9, L11 and L13,respectively, to portions 2274, 2276, 2278, 2280, 2282, 2284 and 2286,respectively, of an upper metal layer D0. D1 and D2 are exampleadditional upper metal layers above D0. Additional contact structuresamong the upper metal layers can also be provided.

FIG. 22C depicts an example alternative terraced portion 2210 of a cellarea with contact structures. This terraced portion includes a terraceor stair steps which are etched in both the x and y directions. Theterraced portion thus extends in two perpendicular directions. As anexample, each conductive layer 2212 to 2217 (such as a metal silicideword line layer) can be connected to a respective portion of an uppermetal layer (not shown) via a respective contact pillar 2222 to 2227,respectively. The dielectric layers are between the conductive layersbut are not depicted for simplicity. Moreover, the terraced portion maybe used for one block, while an adjacent block has a similar but mirrorimage terraced portion. The blocks can be separated by aninsulation-filled slit, as mentioned. This type of terrace configurationcan similarly be provided in any of the other examples.

FIG. 23A depicts a cross-sectional view along line 590 of FIG. 5 of theplane 570, showing terraced portions 2350 and 2352 of the interconnectarea IA1. The interconnect I1 of the interconnect area IA1 is depicted.For example, the terraced portions 2350 and 2352 may be at opposingfirst 2302 and second 2306 sides of the memory device 150 (correspondingto sides 2202 and 2206, respectively, in FIG. 22A). An intermediateregion 2304 extends between the opposing sides. As in FIG. 22A, theterrace has steps at transitions between L1 and L2, L3 and L4, L5 andL6, L7 and L8, L9 and L10, L11 and L12, and L13 and L14. Examplecircuitry 860 is also depicted in a simplified form. The circuitry 860could also be present in the view of FIG. 22A but is not depicted therefor simplicity. The circuitry 860 is depicted in the view of FIG. 23Abecause of its functional relationship to the interconnect area.

FIG. 23B depicts contact structures of the terraced portion 2352 of thecell area CA3 of FIG. 23A. In one approach, a contact structure 2358extends from L1 at the terraced portion 2352. In one approach, a contactstructure 2356 extends from L16 at a top of the interconnect I1, withina perimeter of the stack. The contact structure 2358 extends to aportion 2354 of D0. Additional contact structures among the upper metallayers can also be provided.

In the substrate 190, the contact structure 868, 870 and 872 connect thecircuitry 860 to a bottom portion of the interconnect I1, e.g., at L0.Thus, in one approach, a conductive path is made from the circuitry tothe bottom portion of the interconnect I1, to the contact structure 2358to D0. In another approach, a conductive path is made from the circuitryto the bottom portion of the interconnect, through the interconnect tothe top of the interconnect, and through the contact structure 2356 toD0. A region 2355 represents dielectric in the completed memory device.

FIG. 23C depicts a cross-sectional view along line 440 of a portion ofthe plane 470 of FIG. 4. The interconnect 13 connects circuitry 2380 toa portion 2362 of the upper metal layer D0 using the below-stack contactstructures 2375, 2377 and 2379 and portions 2376 and 2378 of the lowermetal layers M0 and M1, and the above-stack contact structure C3. Theinterconnect I5 connects circuitry 2370 to a portion 2361 of the uppermetal layer D0 using the below-stack contact structures 2365, 2367 and2369 and portions 2366 and 2368 of the lower metal layers M0 and M1, andthe above-stack contact structure C5.

FIG. 24 depicts an end view of the plane 570 of FIG. 5, showing contactstructures. In the cell area CA3, the contact structures which extend tothe portions 2274, 2276, 2278, 2280, 2282, 2284 and 2286 of D0 arerepeated from FIG. 22B. In the interconnect area IA1, the contactstructure which extends to the portion 2354 of D0 is repeated from FIG.23B. Additionally, in the cell area CA4, a number of contact structureswhich extend to portions 2474, 2476, 2478, 2480, 2482, 2484 and 2486 ofD0 are depicted. In this example, separate contact structures are usedin the separate cell areas.

FIG. 25 depicts a top view of a peripheral region of a substrate whichincludes stacked interconnects 2500. In this aspect, the capability tointerconnect a lower metal layer with an upper metal layer is providedat a location on the substrate which is lateral of a 3D stackednon-volatile memory cell array comprising one or more planes such asplanes 160 and 170 of FIG. 1B. The stacked interconnects 2500 can beprovided in the peripheral region 182 and/or 184, for instance.Moreover, this feature can be provided regardless of the presence of anin-plane interconnect. Although, the fabrication of a peripheralinterconnect can occur concurrently, at least in part, and using commonprocess steps, with the fabrication of an in-plane interconnect, so thatefficiencies are achieved.

In this example, insulation-filled slits 2590, 2592, 2594 and 2596 areused to divide the stack into six portions, including interconnects2500, 2510, 2520, 2530, 2540 and 2550, having associated contactstructures 2502, 2512, 2522, 2532, 2542 and 2552, respectively. Thefabrication of the interconnects in the peripheral region can proceedessentially in the same way as for the in-plane interconnects. Theinterconnects can be made of metal silicide, for instance. The patternand size of the slits can be selected to ensure effective silicidation.

FIG. 26A depicts a top view of another embodiment of the plane 570 ofFIG. 5 as plane 2600. In this approach, an interconnect which is notmetal silicide is used. Specifically, the interconnect area 2610 usesthe alternating layers of undoped/lightly doped and doped polysilicon asthe cell areas CA3 and CA4 to provide conductive interconnects I17 andI18. The interconnect I17 has its heavily doped polysilicon layersconnected in parallel by contact structures 2620 to 2626 to one or moreupper metal layers. Similarly, the interconnect I18 has its heavilydoped polysilicon layers connected in parallel by contact structures2640 to 2646 to one or more upper metal layers. This approach canprovide an interconnect with a relatively low resistance due to therelatively low resistance of the heavily doped polysilicon layers. Anadvantage is that silicidation need not be performed.

In another approach, instead of depositing alternating layers ofundoped/lightly doped and heavily doped poly and performing steps toreplace the undoped/lightly doped poly with dielectric, it is possibleto directly deposit alternating layers of dielectric such as SiO2 andheavily doped poly. In another option, it is possible to directlydeposit alternating layers of metal and dielectric, where silicidationis not used to provide the metal. The conductive word line layers (e.g.,heavily doped poly or metal) are then connected in parallel asdescribed.

FIG. 26B depicts a cross-sectional view along line 2690 of FIG. 26A,showing heavily doped polysilicon layers connected in parallel. At aside 2676 of the plane 2600, contact structures 2660, 2662, 2664, 2666,2668, 2670 and 2672 extend from L1, L3, L5, L7, L9, L11 and L13,respectively, to the upper metal layer 2674. The layers L1, L3, L5, L7,L9, L11 and L13 of heavily doped polysilicon are therefore connected inparallel. In one approach, a conductive path is made from the circuitry860 to the bottom layer L0 of the stack, and to the upper metal layer2882 via the other heavily doped polysilicon layers L3, L5, L7, L9, L11and L13. Thus, a signal can be sent from the circuit 860 throughmultiple layers of parallel wires (e.g., made of heavily doped silicidedpoly or metal if the layers are used for word lines) to another part ofthe chip, where this interconnect wire has similar connections asdiscussed to the top (over array metal) or bottom (under array metal).

FIG. 27A depicts a capacitor in a 2D memory device. Passive circuitelements such as capacitors and resistors are necessary for mostintegrated circuits, including high density memory. For instance, anexample capacitor 2700 in a 2D NAND memory device can have twocapacitors connected in parallel. A capacitor comprises two conductiveplates separated by a dielectric layer. One capacitor can be formed by afloating gate polysilicon layer 2706 and an n+ diffusion layer 2710 inthe silicon substrate as the conductive plates, and a tunnel oxide layer2708 as the dielectric. A second capacitor can be formed by a controlgate polysilicon layer 2702 and the floating gate polysilicon layer 2706as the conductive plates, and an intermediate ONO (inter-polydielectric) layer 2704 as the dielectric. V1 and V2 are voltages atrespective terminals of the capacitor. These capacitor layers areavailable as horizontal layers which are deposited during thefabrication process. The total capacitance for a given area of thesubstrate is the sum of the individual capacitances. Specifically,during the fabrication of these layers for a memory cell, the samelayers can be provided laterally of the memory cell such as in aperipheral region and used to provide a passive circuit element. Theportions of the layers in the peripheral region can be at the same or adifferent height above the substrate as the corresponding portions ofthe layers of the memory cells.

However, in a 3D memory device such as 3D NAND, the ONO layer 2704 isnot available because it is deposited as a vertical layer on the memoryhole sidewalls (see FIGS. 14A and 21A). Thus, a portion of the layerdoes not extend into the peripheral region. Instead, a 3D NAND devicecould use a single low-voltage gate oxide capacitor (FIG. 27B). However,the capacitance per unit area of the low voltage gate oxide capacitor isless than that of an ONO capacitor in a 2D floating gate NAND devicecomprised of tunnel and ONO capacitors in parallel, e.g., half as much,resulting in excessive use of the substrate area.

Moreover, the 2D NAND device can use the floating gate polysilicon layeras a resistor, but this layer also is not available in the peripheralarea of a 3D memory device. Or, a poly and/or well resistor can be used.In either case, the resistance per unit area which can be achieved inthe peripheral area of a 3D memory device is relatively small, resultingin excessive use of the substrate area.

These problems are compounded by the need for higher voltages whichrequire larger transistors and passive elements. Reducing the peripheralarea would help reduce overall chip size. The passive circuit elementsdescribed can be used in different type of 3D memory device includingNAND and resistive RAM (ReRAM). Further, the passive circuit elementscan be used in different type of chips, such as logic chips and memorychips.

An example application of a capacitor is in a charge pump circuit whichboosts an external voltage such as 3 V to a high programming voltagesuch as 15 to 25 V.

FIG. 27B depicts a capacitor in a 3D memory device. The capacitor 2750includes a low-voltage gate oxide layer 2754 as a dielectric layerbetween a word line polysilicon layer 2752 and an n+ diffusion layer2756 as the conductive plates. V1 and V2 are voltages at respectiveterminals of the capacitor.

FIG. 28A depicts a top view of one embodiment of a passive device 2800as a capacitor in the peripheral region 182 of the 3D stackednon-volatile memory device 150 of FIG. 1B. A space-efficient passivedevice can be provided by taking advantage of a stacked structure ofalternating layers of a conductive material (such as heavily dopedpolysilicon, which is optionally silicided to transform it to metalsilicide) and a dielectric (such as SiO2, deposited in place of removedundoped/lightly doped poly). Each dielectric layer could comprise asingle dielectric material, or multiple layers of dielectric materials,in this and other embodiments. Every other conductive layer can beconnected in parallel, e.g., odd layers to one potential and even layersto another potential, so that multiple layer capacitors are connected inparallel. The multiple conductive layers of the odd layers areeffectively one conductive plane of an overall capacitor, and themultiple conductive layers of the even layers are effectively anotherconductive plane of an overall capacitor. The total capacitance willtherefore be the sum of the individual capacitances. Due to the verticalarrangement of the stack, a very high capacitance per unit area of thesubstrate can be achieved.

Here, a stacked passive device structure 2800 includes layers L1, L3,L5, L7, L9, L11 and L13 of a conductive material such as heavily dopedpolysilicon or metal silicide. The terraced ends are formed so that theconductive layers are accessible to contacts. The intervening layers ofdielectric (not shown here) are L2, L4, L6, L8, L10 and L12 (see FIGS.29A, 30A and 31A to 31E). L0 is also a dielectric layer. The passivedevice structure 2800 has opposing tiered sides at the top and bottom ofthe figure. Specifically, one side has tiers or steps 2801, 2803, 2805,2807, 2809, 2811 and 2816 at L1, L3, L5, L7, L9, L11 and L13,respectively. In this example, contact structures are provided on oneside of the stack, but other variations are possible. For example,contact structures 2802, 2804, 2806, 2808, 2810, 2812 and 2814 areprovided on tiers 2801, 2803, 2805, 2807, 2809, 2811 and 2816,respectively. Another side of the stack includes tiers 2823, 2825, 2827,2829, 2831 and 2833 at L1, L3, L5, L7, L9, L11 and L13, respectively.

The stacked passive device structure can include a number of holes(e.g., 2930) and/or slits (e.g., 2931). For either a capacitor orresistor, the holes and/or slits are provided to allow a wet etchprocess to remove the undoped/lightly doped polysilicon layer, toperform subsequent deposition of a dielectric, and to optionally performsubsequent silicidation of the heavily doped polysilicon, similar to theprocessing of the memory array as discussed previously. Subsequently,the holes and/or slits are filled with insulation. The holes in thepassive device can be provided using the same memory hole mask andprocess step used for the memory array, in one approach. For acapacitor, the hole pattern density can be a minimum to avoidunnecessarily reducing the capacitor plate area (capacitance isproportional to area holes reduce the area), but the hole patterndensity should be sufficient to remove the undoped/lightly dopedpolysilicon. For a resistor, holes and/or slits can also be used toremove the undoped/lightly doped polysilicon. However, a high densityhole pattern can be used, such as the same pattern as in the memoryarray, to increase resistance. Silicidation need not be performed forthe heavily doped polysilicon in the resistor (since silicidationdecreases resistance).

The use of holes and slits in the passive device allows the introductionof a wet etchant, a dielectric and a metal for silicidation, while alsoallowing close integration with the fabrication of the memory array.However, other types of vertical voids can be used alternatively oradditionally. In one approach, the holes are used to introduce the wetetchant, and the slits are filled with insulation to provide support forthe device when the undoped/lightly doped poly is removed. In oneapproach, the slits are used to introduce the wet etchant, and thememory holes are filled with insulation to provide support for thedevice when the undoped/lightly doped poly is removed.

The holes in the passive device need not be used to create memory cells.The holes can be replacement holes, e.g., simply holes or vertical voidsor columns which are filled with insulation in the completed device.

In the memory array and the passive device, the holes may have agenerally square cross-section when first drawn. After lithography, theybecome more like circles and after an etch, more like cylinders. Also,when a wet etch is used, essentially all of the undoped/lightly dopedpolysilicon layer is removed in the capacitor and resistor embodimentsto avoid short circuits between the conductive plates.

See FIG. 29A for a cross-sectional view along line 2815.

FIG. 28B depicts a top view of another embodiment of a passive device2819 as a resistor in the peripheral region 182 of the 3D stackednon-volatile memory device 150 of FIG. 1B. For a 3D resistor, theconductive layers (e.g., L1, L3, L5, L7, L9, L11 and L13) are connectedin series, end to end, to increase resistance per unit area. In thisdevice, additional contact structures 2822, 2824, 2826, 2828, 2830, 2832and 2834 are provided on tiers 2823, 2825, 2827, 2829, 2831 and 2833 atL1, L3, L5, L7, L9, L11 and L13, respectively. The stacked passivedevice structure can include a number of holes (e.g., 2935) and slits(e.g., 2937). The dielectric layers (e.g., L0, L2, L4, L6, L8, L10 andL12, not shown here) alternate with the conductive layers. See FIG. 30Afor a cross-sectional view along line 2817. Note that the terraced endsare formed so that the conductive layers are accessible to contacts.

FIG. 28C depicts a top view of another embodiment of a passive device2821 as multiple capacitors in the peripheral region 182 of the 3Dstacked non-volatile memory device 150 of FIG. 1B. Insulation-filledslits 2990 and 2899 are provided which divided the stack into fourpassive devices 2818, 2820, 2991 and 2992. The passive device 2818includes tiers 2843, 2845, 2847, 2849, 2851, 2853 and 2835 at conductivelayers L1, L3, L5, L7, L9, L11 and L13, respectively, and contactstructures 2842, 2844, 2846, 2848, 2850, 2852 and 2854, respectively.Here and elsewhere, contacts can be provided using the same method,integration scheme, terrace structure, design rules, and so forth as formemory array connections to word line layers.

The passive device 2820 includes tiers 2873, 2875, 2877, 2879, 2881,2883 and 2836 at L1, L3, L5, L7, L9, L11 and L13, respectively, andcontact structures 2872, 2874, 2876, 2878, 2880, 2882 and 2884,respectively.

The passive device 2991 includes tiers 2857, 2859, 2861, 2863, 2865,2867 and 2837 at L1, L3, L5, L7, L9, L11 and L13, respectively, andcontact structures 2856, 2858, 2860, 2862, 2864, 2866 and 2868,respectively.

The passive device 2838 includes tiers 2887, 2889, 2891, 2893, 2895,2897 and 2899 at L1, L3, L5, L7, L9, L11 and L13, respectively, andcontact structures 2886, 2888, 2890, 2892, 2894, 2896 and 2898,respectively.

This approach allows multiple passive devices to be constructed from acommon stack. The stacked passive device structure can include a numberof holes (e.g., 2933) and slits (e.g., 2899 and 2934).

FIG. 29A depicts a cross-sectional view of the passive device 2800 ofFIG. 28A as a capacitor along line 2815 (portions of the upper metallayer are shown in perspective). The contact structures 2802, 2806, 2810and 2814 extend vertically upward from conductive layers L1, L5, L9 andL13, respectively, to a first common portion 2904 of an upper metallayer D0, so that L1, L5, L9 and L13 are conductive plates of acapacitor which are connected in parallel. The contact structures 2804,2808 and 2812 extend vertically upward from conductive layers L3, L7 andL11, respectively, to a different, second common portion 2902 of theupper metal layer D0, so that L3, L7 and L11 are conductive plates of acapacitor which are connected in parallel. The first 2904 and second2902 common portions of the upper metal layers may be terminals of acapacitor which can be connected to any desired circuitry. This is onepossible implementation, as layouts of one or more metal layers forconnections to capacitor plates can vary in many different ways.

In one possible approach, the terminals are connected to circuitry 2918in the substrate 190. For example, the first common portion 2904 of theupper metal layer D0 can be connected to the circuitry 2918 using acontact structure 2908, a portion 2926 of M1, a contact structure 2924,a portion 2922 of M0 and a contact structure 2920. Similarly, the secondcommon portion 2902 of the upper metal layer D0 can be connected to thecircuitry 2918 using a contact structure 2906, a portion 2910 of M1, acontact structure 2912, a portion 2914 of M0 and a contact structure2916. This is an example only. The circuitry can be, but need not, belocated directly under the passive device 2800.

The contact structures can be formed by extending at least one of thecontact structures (e.g., 2802) from one layer (e.g., L1) of the layersof conductive material to a portion 2904 of the at least one upper metallayer, and extending at least another of the contact structures (e.g.,2806) from another layer (e.g., L5) of the layers of conductive materialto the portion 2904 of the at least one upper metal layer. The formingof the contact structures can comprise extending at least an additionalcontact structure (e.g., 2804) of the contact structures from anadditional layer (e.g., L3) of the layers of conductive material toanother portion 2902 of the at least one upper metal layer, andextending at least a further contact structure (e.g., 2808) of thecontact structures from a further layer (e.g., L7) of the layers ofconductive material to the another portion 2902 of the at least oneupper metal layer.

FIG. 29B depicts a circuit diagram of a capacitor corresponding to FIG.29A. A capacitance C(L1-L5) is provided by conductive plates L1 and L5,a capacitance C(L5-L9) is provided by conductive plates L5 and L9, acapacitance C(L9-L13) is provided by conductive plates L9 and L13, acapacitance C(L3-L7) is provided by conductive plates L3 and L7, and acapacitance C(L7-L11) is provided by conductive plates L7 and L11. Thetotal capacitance is thereforeC(L1-L5)+C(L5-L9)+C(L9-L13)+C(L3-L7)+C(L7-L11). The capacitor has acapacitance which is a function of overlapping areas of the plates,separation distances between the plates, and a dielectric constant ofthe dielectric material. For example, for a parallel plate capacitor,Capacitance=k×∈0×area/separation, or C=k∈0A/d, where: k is the relativedielectric permittivity of dielectric, ∈0 is the permittivity of space(vacuum) 8.854e-12 F/m, A is the capacitor area, and d is the separationbetween plates or the dielectric thickness.

In one example, depending on circuit implementation needs, by properconnection of the plates, we can use a part of layers or all layers fora capacitor, to obtain different capacitances for a capacitor device(from the same 3D capacitor structure) for different circuit elements,depending how many layers are used.

FIG. 30A depicts a cross-sectional view of the passive device 2819 ofFIG. 28B along line 2817 as a resistor (portions of the upper metallayer are shown in perspective). To provide a resistor, the conductivelayers (comprising heavily doped poly or metal silicide) are connectedserially, end to end, so that a conductive path travels a length of eachconductive layer. The length here is a distance in the x direction, fromtiered end to tiered end of the stack. Generally, resistance isproportional to the length of a conductor, and the length is a wiredimension in the direction of current. Each conductive layer becomes aresistive component in a resistor whose resistance is a function of asum of the resistances of the respective conductive layers. In oneapproach, at one of the terraced sides of the passive device, thecontact structures 2802 and 2804 extend vertically upward from L1 andL3, respectively, to a first portion 3006 of D0, the contact structures2806 and 2808 extend vertically upward from L5 and L7, respectively, toa second portion 3008 of D0, the contact structures 2810 and 2812 extendvertically upward from L9 and L11, respectively, to a third portion 3010of D0, and the contact structure 2814 extends vertically upward from L13to a fourth portion 3002 of D0.

Here and elsewhere, D0 can be used to connect to an individual layer. D0can also be used to connect several layers (e.g., plates of a capacitor,or of a resistor). In some implementations, D0 connects to the uppermetal D1, and D1 is used to connect several layers and carry signals.Actual implementation details can depend on layout circuitconvenience/feasibility.

In one example, depending on circuit implementation needs, by properconnection of the plates, a part of one or more layers, or all of one ormore conductive layers, can be used to provide different resistances fora resistor device (from the same 3D resistor structure) for differentcircuit elements, depending how many layers are used. For example, apart of one or more layers can be used to provide a lower resistance,while all of one or more conductive layers can be used to provide ahigher resistance. See, e.g., FIG. 31F which shows two resistors formedfrom different sets of conductive layers.

On another of the terraced sides of the passive device, the contactstructure 2822 extends vertically upward from L1 to a fifth portion 3012of D0, the contact structures 2824 and 2826 extend vertically upwardfrom L3 and L5, respectively, to a sixth portion 3014 of D0, the contactstructures 2828 and 2830 extend vertically upward from L7 and L9,respectively, to a seventh portion 3016 of D0, and the contactstructures 2832 and 2834 extend vertically upward from L11 and L13,respectively, to an eighth portion 3018 of D0.

The contact structures can be provided close to the lateral end of theconductive layers so that the full resistance of the conductive layer isrealized. For example, regions 3005 and 3007 represent opposing ends orsides of the conductive layer L1.

The fifth 3012 and eighth 3018 portions (or the fourth portion 3002,connected to the eight portion 3018) of D0 may be terminals of aresistor which can be connected to any desired circuitry. In onepossible approach, the terminals are connected to circuitry 2918 in thesubstrate 190. For example, the fifth portion 3012 of D0 can beconnected to the circuitry 2918 using a contact structure 3020 whichextends down to the portion 2926 of M1, discussed previously. The fourthportion 3002 of D0 can be connected to the circuitry 2918 using acontact structure 3004 which extends down to the portion 2910 of M1,discussed previously.

In a capacitor or resistor, it is also possible to connect a lower metallayer portion to L1 by using a contact structure which extends throughthe etch stop layer 856, as discussed previously.

As a variation, the shape of the conductive layer can be modified, e.g.,to have a serpentine shape, with a goal of increasing the resistance.There are a variety of possible implementations of shapes andconnections. Also, the back gate can be used as a resistor. A back gateplate can be added to the conductive word line plates to form amulti-layer resistor. A back gate layer can be used as an individualresistor, or as a part of 3D resistor. Similarly, select gate polyplates can also be used for a resistor, either separately, or as a partof 3D stacked resistor.

The stack has opposing first 3101 (FIG. 31F) and second 3103 sides, andthe forming a plurality of contact structures comprises: extending atleast one of the contact structures (e.g., 2802) at the first side fromone layer (e.g., L1) of the layers of conductive material to a portion(e.g., 3006) of the at least one upper metal layer, extending at leastanother of the contact structures (e.g., 2804) at the first side fromanother layer (e.g., L3) of the layers of conductive material to theportion (e.g., 3006) of the at least one upper metal layer, extending atleast one of the contact structures (e.g., 2824) at the second side fromthe another layer (e.g., L3) of the layers of conductive material toanother portion (e.g., 3014) of the at least one upper metal layer, andextending at least another of the contact structures (e.g., 2826) at thesecond side from an additional layer (e.g., L5) of the layers ofconductive material to the another portion (e.g., 3014) of the at leastone upper metal layer, where the another layer (e.g., L3) is above theone layer (e.g., L1) and the additional layer (e.g., L5) is above theanother layer (e.g., L3).

FIG. 30B depicts a circuit diagram of a resistor corresponding to FIG.30A. A series chain of resistances R(L1), R(L3), R(L5), R(L7), R(L9),R(L11) and R(L13) is provided by the conductive layer L1, L3, L5, L7,L9, L11 and L13, respectively.

FIG. 31A depicts one embodiment of a passive device as a capacitorformed by a stack of alternating layers of a conductive material and adielectric material, with contacts on a first side of the stack. Thiscorresponds to the arrangement of FIG. 29A. Having the contactstructures on one side is useful, for instance, to provide an efficientlayout, or when only one terraced side of the passive device is exposed,as in the embodiment of FIG. 28C. A passive device 3100 has terminals3102 and 3108 and includes, on one side 3101, a conductive path 3104which connects L1, L5, L9 and L13, and a conductive path 3106 whichconnects L3, L7 and L11. The conductive paths can be formed, e.g., bycontact structures, and upper and lower metal layer structures.

FIG. 31B depicts one embodiment of a passive device 3120 as a capacitorformed by a stack of alternating layers of a conductive material and adielectric material, with contacts on opposing first and second sides ofthe stack. The passive device has terminals 3122 and 3128 and includes,on one side 3101, a conductive path 3124 which connects L1, L5, L9 andL13, and on another side 3103, a conductive path 3106 which connects L3,L7 and L11.

FIG. 31C depicts one embodiment of a passive device 3140 as first andsecond capacitors formed by a stack of alternating layers of aconductive material and a dielectric material. This is an example ofhaving multiple passive devices in one stack. A first capacitor hasterminals 3141 and 3146, and is formed by L9 and L13, connected by aconductive path 3142, and L3, L7 and L11, connected by a conductive path3145 (at the opposing side 3103 of the device). A second capacitor hasterminals 3144 and 3146, and is formed by L1 and L5, connected by aconductive path 3143, and L3, L7 and L11, connected by a conductive path3145.

FIG. 31D depicts one embodiment of a passive device 3160 which includesa resistor above a capacitor, formed by a stack of alternating layers ofa conductive material and a dielectric material. A resistor hasterminals 3161 and 3166 and is formed by resistive components (e.g.,conductive plates) L9, L11 and L13, connected serially by conductivepaths 3162 and 3165. A capacitor has terminals 3164 and 3168 andincludes conductive plates L1 and L5 connected by a conductive path3163, and conductive plates L3 and L7 connected by a conductive path3167. This approach allows two types of passive devices to be fabricatedin the same area of the substrate, providing flexibility andspace-efficiency. For example, a resistor and a capacitor can bevertically arranged.

The alternating layers can comprise at least first (e.g., L1, L3, L5 andL7) and second (e.g., L9, L11 and L13) sets of the alternating layers.Forming the plurality of contact structures comprises forming a firstset of contact structures (3163, 3167) associated with the first set ofthe alternating layers, and a second set of contact structures (3162,3165) associated with the second set of the alternating layers. Thelayers of conductive material in the first set of the alternating layerscan be connected to one another in parallel by the first set of contactstructures, and the layers of conductive material in the second set ofthe alternating layers can be connected to one another serially by thesecond set of contact structures, separate from the first set of thealternating layers.

FIG. 31E depicts one embodiment of a passive device 3170 as a resistorformed by a stack of alternating layers of a conductive material and adielectric material. This corresponds to the resistor of FIG. 30A. Aresistor has terminals 3171 and 3178, and includes resistive components(e.g., conductive plates) L1, L3, L5, L7, L9, L11 and L13 connectedserially, end to end, by conductive paths 3172 to 3177.

In a further option, a “vertical” resistor can be comprised of a stackof undoped/lightly doped poly and heavily doped poly which is notsilicided, with contacts provided on the bottom and top of the stack.Multiples of such vertical resistors can be connected in series, toachieve a high resistivity.

FIG. 31F depicts one embodiment of a passive device 3158 as tworesistors formed by a stack of alternating layers of a conductivematerial and a dielectric material. One resistor R1 has terminals 3181and 3184, and includes resistive components (e.g., conductive plates)L9, L11 and L13 connected serially by conductive paths 3182 and 3183.Another resistor R2 has terminals 3185 and 3189, and includes resistivecomponent L1, L3, L5 and L7 connected serially by conductive paths 3186,3187 and 3188. This approach allows multiple resistor devices to befabricated in the same area of the substrate and vertically arranged. Inthis example, R2>R1 since R2 includes four conductive players instead ofthree. That is, R2/R1=4/3. Optionally, when the conductive layers areheavily doped poly, the amount of doping can be adjusted to adjust theamount of resistance (e.g., higher doping=lower resistance), when one ormore resistors are formed in a stack.

The alternating layers can comprise at least first (e.g., L1, L3, L5 andL7) and second (e.g., L9, L11 and L13) sets of the alternating layers.Forming the plurality of contact structures comprises forming a firstset of contact structures (3186 to 3188) associated with the first setof the alternating layers, and a second set of contact structures (3182,3183) associated with the second set of the alternating layers. Thelayers of conductive material in the first set of the alternating layerscan be connected to one another serially by the first set of contactstructures, and the layers of conductive material in the second set ofthe alternating layers can be connected to one another serially by thesecond set of contact structures, separate from the first set of thealternating layers.

FIG. 32A depicts a method for fabricating a passive device as acapacitor in a peripheral region of a 3D stacked non-volatile memorydevice according to the structures of FIGS. 28A to 31E, where a wet etchis performed via slits.

The steps include: Provide below-stack circuitry and metal layers onsubstrate, 3200; Provide etch stop layer with bottom gate, 3202; Deposita stack of alternating layers of undoped/lightly doped and heavily dopedpolysilicon in a peripheral region of substrate, 3204; Etch holes andslits in the peripheral region, 3206; Fill in the holes with insulation,3208; Perform a wet etch via the slits to remove the undoped/lightlydoped polysilicon layers in the peripheral region, 3210; Depositinsulation in the slits, (also filling the recesses formed in step 3210)3212; Clean out the slits, 3214; Perform silicidation of the heavilydoped polysilicon layers via the slits to form metal silicide layers,3216; Deposit insulation in the slits, 3218; Form contact structures inthe peripheral region which extend from the metal silicide layers to anabove-stack metal layer, connecting the metal silicide layers inparallel, 3220; and Form contact structures in the peripheral regionwhich extend from the above-stack metal to a below-stack metal layer, tocomplete a circuit 3222. In step 3212, the insulation deposited in theslits extends horizontally to fill the recesses formed in step 3210.

Moreover, a number of the processes for fabricating the passive devicecan be carried out concurrently, at least in part, with the analogousprocesses for fabricating a 3D stacked memory array.

This approach uses replacement holes to anchor the heavily doped polylayers when the undoped/lightly doped poly layers are removed. The slitsare used for wet etch and undoped/lightly doped poly removal. Insulationdeposited into the slits is also deposited in between the heavily dopedpoly layers. The slits are then cleaned up and silicidation isperformed.

In another possible approach, after the wet etch via the slits andremoval of the undoped/lightly doped poly layers, silicidation isperformed right away, e.g. by Ni CVD. In this approach, the silicidationaffects not only the vertical edges of heavily doped poly layers, butalso extends laterally along heavily doped poly boundaries and voidsleft after undoped/lightly doped poly removal. This is desirable for acapacitor because of the lower resistance of the poly plates. This isnot desirable for a resistor where a higher resistance is sought. Aftersilicidation, the slits and voids between the heavily doped poly (nowmetal silicide) layers are filled in with an insulator.

FIG. 32B depicts a method for fabricating a passive device as acapacitor in a peripheral region of a 3D stacked non-volatile memorydevice according to the structures of FIGS. 28A to 31E, where a wet etchis performed via holes. These steps are an alternative to steps 3208 to3218 of FIG. 32A. The steps include: Fill in the slits with insulation,3224; Perform a wet etch via the holes to remove the undoped/lightlydoped polysilicon layers in the peripheral region, 3226; Depositinsulation in the memory holes (also filling the recesses formed in step3226), 3228; Clean out the holes, 3230; Perform silicidation of theheavily doped polysilicon layers via the holes, 3232; and Depositinsulation in the holes, 3234. In step 3228, the dielectric deposited inthe holes extends horizontally or laterally to fill the recesses formedin step 3226.

In another possible approach, once insulation is deposited in the holes,the same process which is used in the memory array can be performed.That is, ONO insulation layers can be deposited in the replacement holesand, at the same time, extend between the poly layers. Then, the slitsare opened, and silicidation is done via the slits. Then, insulator isput into the slits. This approach allows the same process step ofdepositing ONO insulation to be performed concurrently in both thememory array area and in one or more peripheral areas.

FIG. 33A depicts a method for fabricating a passive device as a resistorin a peripheral region of a 3D stacked non-volatile memory deviceaccording to the structures of FIGS. 28A to 31E, where a wet etch isperformed via slits. The steps include: Provide below-stack circuitryand metal layers on substrate, 3300; Provide etch stop layer with bottomgate, 3302; Deposit a stack of alternating layers of undoped/lightlydoped and heavily doped polysilicon in a peripheral region of substrate,3304; Etch holes and slits in the peripheral region, 3306; Fill in theholes with insulation, 3308; Perform a wet etch via the slits to removethe undoped/lightly doped polysilicon layers in the peripheral region,3310; Deposit insulation in the slits (also filling in the recessesformed in step 3310), 3312; Form contact structures in the peripheralregion which extend from the heavily doped polysilicon layers to anabove-stack metal layer, connecting the heavily doped polysilicon layersin parallel, 3320; and Form contact structures in the peripheral regionwhich extend from the above-stack metal to a below-stack metal layer, tocomplete a circuit 3322. In step 3312, the insulation deposited in theslits extends horizontally or laterally to fill the recesses formed instep 3310.

FIG. 33B depicts a method for fabricating a passive device as a resistorin a peripheral region of a 3D stacked non-volatile memory deviceaccording to the structures of FIGS. 28A to 31E, where a wet etch isperformed via holes. These steps an alternative to steps 3308 to 3312 ofFIG. 33A. The steps include: Fill in the slits with insulation, 3324;Perform a wet etch via the holes to remove the undoped/lightly dopedpolysilicon layers in the peripheral region, 3326; and Depositinsulation in the holes, 3328. In step 3328, the insulation deposited inthe holes extends horizontally to fill the recesses formed in step 3326.

Thus, the layers of the passive device can be formed during the normalmemory array process flow for forming word line planes. The number oflayers of the passive device can correspond to that of the memory array.Contact structures on one or both sides of the passive device can beused. Contact structures on one side uses less area. Connections to theword line planes can be done using the same process flow (terraceformation) as for the memory array word line connection hook-up. Or,when the passive device consumes a larger area, connections can be madeusing one side stepping (one tiered side of the stack) for all layers.Moreover, the slit mask can be modified to form the multiple word lineplate-based capacitor. The poly etch mark for the contact areaformation, and the mark for the upper metal layers D0 and D1, can bemodified for word line plate connections for capacitors. The same wordline hook-up terrace process can be used for contacting the poly layers.Other implementations possible.

Thus, the same memory hole mask (or hole replacement mask) and slit maskcan be used to form a passive device (capacitor and/or resistor) in theperiphery, using the same process as in the array (terrace) to makeconnections to passive devices. For connections, the same D0, D1 masks,terrace contact mask and other contact masks (e.g. to connect from overto under array e.g. D0 to M1)—all masks modified—can be used to makeconnections and carry signals to/from a passive device. Optionally, asmentioned, for a resistor, the conductive layers can remain as heavilydoped poly layers and need not be silicided. As mentioned, the higherresistance of heavily doped compared to metal silicide in a conductivelayer is an advantage for a resistor, while the lower resistance ofmetal silicide compared to heavily doped poly in a conductive layer isan advantage for a capacitor.

In one embodiment, a passive device includes: (a) a stack formed on asubstrate, the stack comprising alternating layers of a dielectricmaterial and a conductive material, the stack is formed in a peripheralregion of the substrate, lateral of a 3D stacked non-volatile memorycell array on the substrate; (b) at least one upper metal layer above atop layer of the stack; and (c) a plurality of contact structures whichextend from at least three layers of the conductive material to the atleast one upper metal layer, the layers of conductive material areconnected to one another in parallel or serially by the plurality ofcontact structures and the at least one upper metal layer.

In another embodiment, a passive device includes: (a) a stack formed ona substrate, the stack comprising alternating layers of a dielectricmaterial and a conductive material; (b) at least one insulation-filledslit which divides the stack into at least first and second portions;(c) at least one upper metal layer above a top layer of the stack; (d) aplurality of contact structures associated with the first portion whichextend from the layers of conductive material in the first portion tothe at least one upper metal layer, the layers of conductive material inthe first portion are connected to one another in parallel or seriallyby the plurality of contact structures associated with the first portionand the at least one upper metal layer; and (e) a plurality of contactstructures associated with the second portion which extend from thelayers of conductive material in the second portion to the at least oneupper metal layer, the layers of conductive material in the secondportion are connected to one another in parallel or serially by theplurality of contact structures associated with the second portion andthe at least one upper metal layer.

In another embodiment, a passive device includes: (a) a stack formed ona substrate, the stack comprising alternating layers of a dielectricmaterial and a conductive material, the stack is formed in a peripheralregion of the substrate, lateral of a 3D stacked non-volatile memorycell array on the substrate, and the alternating layers of theconductive material and the dielectric material comprise at least afirst set of the alternating layers, and a second set of the alternatinglayers above or below the first set of the alternating layers; (b) afirst set of contact structures associated with the first set of thealternating layers; and (c) a second set of contact structuresassociated with the second set of the alternating layers, the layers ofconductive material in the first set of the alternating layers areconnected to one another in parallel or serially by the first set ofcontact structures and the at least one upper metal layer, and thelayers of conductive material in the second set of the alternatinglayers are connected to one another in parallel or serially by thesecond set of contact structures and the at least one upper metal layer,separate from the first set of the alternating layers.

The foregoing detailed description of the technology herein has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the technology to the precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. The described embodiments were chosen to bestexplain the principles of the technology and its practical applicationto thereby enable others skilled in the art to best utilize thetechnology in various embodiments and with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the technology be defined by the claims appended hereto.

What is claimed is:
 1. A passive device, comprising: a stack formed on asubstrate, the stack comprising alternating layers of a conductivematerial and a dielectric material, the stack is formed in a peripheralregion of the substrate, lateral of a 3D stacked non-volatile memorycell array on the substrate, and the alternating layers of theconductive material and the dielectric material comprise at least afirst set of the alternating layers, and a second set of the alternatinglayers above or below the first set of the alternating layers andarranged vertically with the first set of the alternating layers, thefirst set of the alternating layers is part of a first passive deviceand the second set of the alternating layers is part of a second passivedevice; a first set of contact structures associated with the first setof the alternating layers; and a second set of contact structuresassociated with the second set of the alternating layers, the layers ofconductive material in the first set of the alternating layers areconnected to one another in parallel or serially by the first set ofcontact structures and the at least one upper metal layer, and thelayers of conductive material in the second set of the alternatinglayers are connected to one another in parallel or serially by thesecond set of contact structures and the at least one upper metal layer,separate from the first set of the alternating layers, wherein: thefirst set of the alternating layers are connected to one another inparallel; and the layers of conductive material in the first set of thealternating layers are plates of a capacitor as the first passivedevice; the second set of the alternating layers are connected to oneanother serially; and the layers of conductive material in the secondset of the alternating layers are resistive components of a resistor asthe second passive device.
 2. The passive device of claim 1, furthercomprising: at least one insulation-filled slit or insulation-filledhole which extends vertically within the stack, the conductive materialcomprises metal silicide; and the dielectric material comprises at leastone of oxide, nitride or a combination of oxide and nitride.
 3. Thepassive device of claim 1, wherein: the conductive material comprisesheavily doped polysilicon having a doping concentration of 10^20 to10^21 cm-3 or more; and the dielectric material comprises at least oneof oxide, nitride or a combination of oxide and nitride.